Posts Tagged ‘Johns Hopkins’


Illustration of how pH imbalance inside endosomes may contribute to Alzheimer’s disease

Johns Hopkins Medicine scientists say they have found new evidence in lab-grown mouse brain cells, called astrocytes, that one root of Alzheimer’s disease may be a simple imbalance in acid-alkaline—or pH—chemistry inside endosomes, the nutrient and chemical cargo shuttles in cells.

Astrocytes work to clear so-called amyloid beta proteins from the spaces between neurons, but decades of evidence has shown that if the clearing process goes awry, amyloid proteins pile up around neurons, leading to the characteristic amyloid plaques and nerve cell degeneration that are the hallmarks of memory-destroying Alzheimer’s disease.

The new study, described online June 26 in Proceedings of the National Academy of Sciences, also reports that the scientists gave drugs called histone deacetylase (HDAC) inhibitors to pH-imbalanced mice cells engineered with a common Alzheimer’s gene variant. The experiment successfully reversed the pH problem and improved the capacity for amyloid beta clearance.

HDAC inhibitors are approved by the U.S. Food and Drug Administration for use in people with certain types of blood cancers, but not in people with Alzheimer’s. They cautioned that most HDAC inhibitors cannot cross the blood-brain barrier, a significant challenge to the direct use of the drugs for brain disorders. The scientists say they are planning additional experiments to see if HDAC inhibitors have a similar effect in lab-grown astrocytes from Alzheimer’s patients, and that there is the potential to design HDAC inhibitors that can cross the barrier.

However, the scientists caution that even before those experiments can happen, far more research is needed to verify and explain the precise relationship between amyloid proteins and Alzheimer’s disease, which affects an estimated 50 million people worldwide. To date, there is no cure and no drugs that can predictably or demonstrably prevent or reverse Alzheimer’s disease symptoms.

“By the time Alzheimer’s disease is diagnosed, most of the neurological damage is done, and it’s likely too late to reverse the disease’s progression,” says Rajini Rao, Ph.D., professor of physiology at the Johns Hopkins University School of Medicine. “That’s why we need to focus on the earliest pathological symptoms or markers of Alzheimer’s disease, and we know that the biology and chemistry of endosomes is an important factor long before cognitive decline sets in.”

Nearly 20 years ago, scientists at Johns Hopkins and New York University discovered that endosomes, circular compartments that ferry cargo within cells, are larger and far more abundant in brain cells of people destined to develop Alzheimer’s disease. This hinted at an underlying problem with endosomes that could lead to an accumulation of amyloid protein in spaces around neurons, says Rao.

To shuttle their cargo from place to place, endosomes use chaperones—proteins that bind to specific cargo and bring them back and forth from the cell’s surface. Whether and how well this binding occurs depends on the proper pH level inside the endosome, a delicate balance of acidity and alkalinity, or acid and base, that makes endosomes float to the surface and slip back down into the cell.

Embedded in the endosome membrane are proteins that shuttle charged hydrogen atoms, known as protons, in and out of endosomes. The amount of protons inside the endosome determines its pH.

When fluids in the endosome become too acidic, the cargo is trapped within the endosome deep inside the cell. When the endosome contents are more alkaline, the cargo lingers at the cell’s surface for too long.

To help determine whether such pH imbalances occur in Alzheimer’s disease, Johns Hopkins graduate student Hari Prasad scoured scientific studies of Alzheimer’s disease looking for genes that were dialed down in diseased brains compared with normal ones. Comparing a dataset of 15 brains of Alzheimer’s disease patients with 12 normal ones, he found that 10 of the 100 most frequently down-regulated genes were related to the proton flow in the cell.

In another set of brain tissue samples from 96 people with Alzheimer’s disease and 82 without it, gene expression of the proton shuttle in endosomes, known as NHE6, was approximately 50 percent lower in people with Alzheimer’s disease compared with those with normal brains. In cells grown from people with Alzheimer’s disease and in mouse astrocytes engineered to carry a human Alzheimer’s disease gene variant, the amount of NHE6 was about half the amount found in normal cells.

To measure the pH balance within endosomes without breaking open the astrocyte, Prasad and Rao used pH sensitive probes that are absorbed by endosomes and emit light based on pH levels. They found that mouse cell lines containing the Alzheimer’s disease gene variant had more acidic endosomes (average of 5.37 pH) than cell lines without the gene variant (average of 6.21 pH).

“Without properly functioning NHE6, endosomes become too acidic and linger inside astrocytes, avoiding their duties to clear amyloid beta proteins,” says Rao.

While it’s likely that changes in NHE6 happen over time in people who develop sporadic Alzheimer’s disease, people who have inherited mutations in NHE6 develop what’s known as Christianson syndrome in infancy and have rapid brain degeneration.

Prasad and Rao also found that a protein called LRP1, which picks up amyloid beta proteins outside the astrocyte and delivers them to endosomes, was half as abundant on the surface of lab grown mouse astrocytes engineered with a human gene variant called APOE4, commonly linked to Alzheimer’s disease.

Looking for ways to restore the function of NHE6, Prasad searched databases of yeast studies to find that HDAC inhibitors tend to increase expression of the NHE6 gene in yeast. This gene is very similar across species, including flies, mice and humans.

Prasad and Rao tested nine types of HDAC inhibitors on cell cultures of mouse astrocytes engineered with the APOE4 gene variant. Broad-spectrum HDAC inhibitors increased NHE6 expression to levels associated with mouse astrocytes that did not have the Alzheimer’s gene variant. They also found that HDAC inhibitors corrected the pH imbalance inside endosomes and restored LRP1 to the astrocyte surface, resulting in efficient clearance of amyloid beta protein.

More information: Hari Prasad et al. Amyloid clearance defect in ApoE4 astrocytes is reversed by epigenetic correction of endosomal pH, Proceedings of the National Academy of Sciences (2018). DOI: 10.1073/pnas.1801612115

https://medicalxpress.com/news/2018-08-ph-imbalance-brain-cells-contribute.html

By Richard Schiffman

In one of the largest and most rigorous clinical investigations of psychedelic drugs to date, researchers at Johns Hopkins University and New York University have found that a single dose of psilocybin—the psychoactive compound in “magic” mushrooms—substantially diminished depression and anxiety in patients with advanced cancer.

Psychedelics were the subject of a flurry of serious medical research in the 1960s, when many scientists believed some of the mind-bending compounds held tremendous therapeutic promise for treating a number of conditions including severe mental health problems and alcohol addiction. But flamboyant Harvard psychology professor Timothy Leary—one of the top scientists involved—started aggressively promoting LSD as a consciousness expansion tool for the masses, and the youth counterculture movement answered the call in a big way. Leary lost his job and eventually became an international fugitive. Virtually all legal research on psychedelics shuddered to a halt when federal drug policies hardened in the 1970s.

The decades-long research blackout ended in 1999 when Roland Griffiths of Johns Hopkins was among the first to initiate a new series of studies on psilocybin. Griffiths has been called the grandfather of the current psychedelics research renaissance, and a 21st-century pioneer in the field—but the soft-spoken investigator is no activist or shaman/showman in the mold of Leary. He’s a scientifically cautious clinical pharmacologist and author of more than 300 studies on mood-altering substances from coffee to ketamine.

Much of Griffiths’ fascination with psychedelics stems from his own mindfulness meditation practice, which he says sparked his interest in altered states of consciousness. When he started administering psilocybin to volunteers for his research, he was stunned that more than two-thirds of the participants rated their psychedelic journey one of the most important experiences of their lives.

Griffiths believes that psychedelics are not just tools for exploring the far reaches of the human mind. He says they show remarkable potential for treating conditions ranging from drug and alcohol dependence to depression and post-traumatic stress disorder.

They may also help relieve one of humanity’s cruelest agonies: the angst that stems from facing the inevitability of death. In research conducted collaboratively by Griffiths and Stephen Ross, clinical director of the NYU Langone Center of Excellence on Addiction, 80 patients with life-threatening cancer in Baltimore and New York City were given laboratory-synthesized psilocybin in a carefully monitored setting, and in conjunction with limited psychological counseling. More than three-quarters reported significant relief from depression and anxiety—improvements that remained during a follow-up survey conducted six months after taking the compound, according to the double-blind study published December 1 in The Journal of Psychopharmacology.

“It is simply unprecedented in psychiatry that a single dose of a medicine produces these kinds of dramatic and enduring results,” Ross says. He and Griffiths acknowledge that psychedelics may never be available on the drugstore shelf. But the scientists do envision a promising future for these substances in controlled clinical use. In a wide-ranging interview, Griffiths told Scientific American about the cancer study and his other work with psychedelics—a field that he says could eventually contribute to helping ensure our survival as a species.

[An edited transcript of the interview follows.]

What were your concerns going into the cancer study?
The volunteers came to us often highly stressed and demoralized by their illness and the often-grueling medical treatment. I felt very cautious at first, wondering if this might not re-wound people dealing with the painful questions of death and dying. How do we know that this kind of experience with this disorienting compound wouldn’t exacerbate that? It turns out that it doesn’t. It does just the opposite. The experience appears to be deeply meaningful spiritually and personally, and very healing in the context of people’s understanding of their illness and how they manage that going forward.

Could you describe your procedure?
We spent at least eight hours talking to people about their cancer, their anxiety, their concerns and so on to develop good rapport with them before the trial. During the sessions there was no specific psychological intervention—we were just inviting people to lie on the couch and explore their own inner experience.

What did your research subjects tell you about that experience?
There is something about the core of this experience that opens people up to the great mystery of what it is that we don’t know. It is not that everybody comes out of it and says, ‘Oh, now I believe in life after death.’ That needn’t be the case at all. But the psilocybin experience enables a sense of deeper meaning, and an understanding that in the largest frame everything is fine and that there is nothing to be fearful of. There is a buoyancy that comes of that which is quite remarkable. To see people who are so beaten down by this illness, and they start actually providing reassurance to the people who love them most, telling them ‘it is all okay and there is no need to worry’— when a dying person can provide that type of clarity for their caretakers, even we researchers are left with a sense of wonder.

Was this positive result universal?
We found that the response was dose-specific. The larger dose created a much larger response than the lower dose. We also found that the occurrence of mystical-type experiences is positively correlated with positive outcomes: Those who underwent them were more likely to have enduring, large-magnitude changes in depression and anxiety.

Did any of your volunteers experience difficulties?
There are potential risks associated with these compounds. We can protect against a lot of those risks, it seems, through the screening and preparation procedure in our medical setting. About 30 percent of our people reported some fear or discomfort arising sometime during the experience. If individuals are anxious, then we might say a few words, or hold their hand. It is really just grounding them in consensual reality, reminding them that they have taken psilocybin, that everything is going to be alright. Very often these short-lived experiences of psychological challenge can be cathartic and serve as doorways into personal meaning and transcendence—but not always.

Where do you go from here?
The Heffter Research Institute, which funded our study, has just opened a dialogue with the FDA (Food and Drug Administration) about initiating a phase 3 investigation. A phase 3 clinical trial is the gold standard for determining whether something is clinically efficacious and meets the standards that are necessary for it to be released as a pharmaceutical. Approval would be under very narrow and restrictive conditions initially. The drug might be controlled by a central pharmacy, which sends it to clinics that are authorized to administer psilocybin in this therapeutic context. So this is not writing a prescription and taking it home. The analogy would be more like an anesthetic being dispensed and managed by an anesthesiologist.

You are also currently conducting research on psilocybin and smoking.
We are using psilocybin in conjunction with cognitive behavioral therapy with cigarette smokers to see if these deeply meaningful experiences that can happen with psilocybin can be linked with the intention and commitment to quit smoking, among people who have failed repeatedly to do so. Earlier we ran an uncontrolled pilot study on that in 50 volunteers, in which we had 80 percent abstinence rates at six months. Now we are doing a controlled clinical trial in that population.

How do you account for your remarkable initial results?
People who have taken psilocybin appear to have more confidence in their ability to change their own behavior and to manage their addictions. Prior to this experience, quite often the individual feels that they have no freedom relative to their addiction, that they are hooked and they don’t have the capacity to change. But after an experience of this sort—which is like backing up and seeing the larger picture—they begin to ask themselves ‘Why would I think that I couldn’t stop cigarette smoking? Why would I think that this craving is so compelling that I have to give in to it?’ When the psilocybin is coupled with cognitive behavioral therapy, which is giving smokers tools and a framework to work on this, it appears to be very helpful.

You are also working with meditation practitioners. Are they having similar experiences?
We have done an unpublished study with beginning meditators. We found that psilocybin potentiates their engagement with their spiritual practice, and it appears to boost dispositional characteristics like gratitude, compassion, altruism, sensitivity to others and forgiveness. We were interested in whether the psilocybin used in conjunction with meditation could create sustained changes in people that were of social value. And that appears to be the case.

So it is actually changing personality?
Yes. That is really interesting because personality is considered to be a fixed characteristic; it is generally thought to be locked down in an individual by their early twenties. And yet here we are seeing significant increases in their “openness” and other pro-social dimensions of personality, which are also correlated with creativity, so this is truly surprising.

Do we know what is actually happening in the brain?
We are doing neuro-imaging studies. Dr. Robin Carhart-Harris’s group at Imperial College in London is also doing neuro-imaging studies. So it is an area of very active investigation. The effects are perhaps explained, at least initially, by changes in something [in the brain] called “the default mode network,” which is involved in self-referential processing [and in sustaining our sense of ego]. It turns out that this network is hyperactive in depression. Interestingly, in meditation it becomes quiescent, and also with psilocybin it becomes quiescent. This may correlate with the experience of clarity of coming into the present moment.

That is perhaps an explanation of the acute effects, but the enduring effects are much less clear, and I don’t think that we have a good handle on that at all. Undoubtedly it is going to be much more complex than just the default mode network, because of the vast interconnectedness of brain function.

What are the practical implications of this kind of neurological and therapeutic knowledge of psychedelics?
Ultimately it is not really about psychedelics. Science is going to take it beyond psychedelics when we start understanding the brain mechanisms underlying this and begin harnessing these for the benefit of humankind.

The core mystical experience is one of the interconnectedness of all people and things, the awareness that we are all in this together. It is precisely the lack of this sense of mutual caretaking that puts our species at risk right now, with climate change and the development of weaponry that can destroy life on the planet. So the answer is not that everybody needs to take psychedelics. It is to understand what mechanisms maximize these kinds of experiences, and to learn how to harness them so that we don’t end up annihilating ourselves.

https://www.scientificamerican.com/article/psilocybin-a-journey-beyond-the-fear-of-death/

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While researching the brain’s learning and memory system, scientists at Johns Hopkins say they stumbled upon a new type of nerve cell that seems to control feeding behaviors in mice. The finding, they report, adds significant detail to the way brains tell animals when to stop eating and, if confirmed in humans, could lead to new tools for fighting obesity. Details of the study were published by the journal Science today.

“When the type of brain cell we discovered fires and sends off signals, our laboratory mice stop eating soon after,” says Richard Huganir, Ph.D., director of the Department of Neuroscience at the Johns Hopkins University School of Medicine. “The signals seem to tell the mice they’ve had enough.”

Huganir says his team’s discovery grew out of studies of the proteins that strengthen and weaken the intersections, or synapses, between brain cells. These are an important target of research because synapse strength, particularly among cells in the hippocampus and cortex of the brain, is important in learning and memory.

In a search for details about synapse strength, Huganir and graduate student Olof Lagerlöf, M.D., focused on the enzyme OGT — a biological catalyst involved in many bodily functions, including insulin use and sugar chemistry. The enzyme’s job is to add a molecule called N-acetylglucosamine (GlcNAc), a derivative of glucose, to proteins, a phenomenon first discovered in 1984 by Gerald Hart, Ph.D., director of the Johns Hopkins University School of Medicine’s Department of Biological Chemistry and co-leader of the current study. By adding GlcNAc molecules, OGT alters the proteins’ behavior.

To learn about OGT’s role in the brain, Lagerlöf deleted the gene that codes for it from the primary nerve cells of the hippocampus and cortex in adult mice. Even before he looked directly at the impact of the deletion in the rodents’ brains, Lagerlöf reports, he noticed that the mice doubled in weight in just three weeks. It turned out that fat buildup, not muscle mass, was responsible.

When the team monitored the feeding patterns of the mice, they found that those missing OGT ate the same number of meals — on average, 18 a day — as their normal littermates but tarried over the food longer and ate more calories at each meal. When their food intake was restricted to that of a normal lab diet, they no longer gained extra weight, suggesting that the absence of OGT interfered with the animals’ ability to sense when they were full.

“These mice don’t understand that they’ve had enough food, so they keep eating,” says Lagerlöf.

Because the hippocampus and cortex are not known to directly regulate feeding behaviors in rodents or other mammals, the researchers looked for changes elsewhere in the brain, particularly in the hypothalamus, which is known to control body temperature, feeding, sleep and metabolism. There, they found OGT missing from a small subset of nerve cells within a cluster of neurons called the paraventricular nucleus.

Lagerlöf says these cells already were known to send and receive multiple signals related to appetite and food intake. When he looked for changes in the levels of those factors that might be traced to the absence of OGT, he found that most of them were not affected, and the activity of the appetite signals that many other research groups have focused on didn’t seem to be causing the weight gain, he adds.

Next, the team examined the chemical and biological activity of the OGT-negative cells. By measuring the background electrical activity in nonfiring brain cells, the researchers estimated the number of incoming synapses on the cells and found that they were three times as few, compared to normal cells.

“That result suggests that, in these cells, OGT helps maintain synapses,” says Huganir. “The number of synapses on these cells was so low that they probably aren’t receiving enough input to fire. In turn, that suggests that these cells are responsible for sending the message to stop eating.”

To verify this idea, the researchers genetically manipulated the cells in the paraventricular nucleus so that they would add blue light-sensitive proteins to their membranes. When they stimulated the cells with a beam of blue light, the cells fired and sent signals to other parts of the brain, and the mice decreased the amount they ate in a day by about 25 percent.

Finally, because glucose is needed to produce GlcNAc, they thought that glucose levels, which increase after meals, might affect the activity of OGT. Indeed, they found that if they added glucose to nerve cells in petri dishes, the level of proteins with the GlcNAc addition increased in proportion to the amount of glucose in the dishes. And when they looked at cells in the paraventricular nucleus of mice that hadn’t eaten in a while, they saw low levels of GlcNAc-decorated proteins.

“There are still many things about this system that we don’t know,” says Lagerlöf, “but we think that glucose works with OGT in these cells to control ‘portion size’ for the mice. We believe we have found a new receiver of information that directly affects brain activity and feeding behavior, and if our findings bear out in other animals, including people, they may advance the search for drugs or other means of controlling appetites.”

http://www.eurekalert.org/pub_releases/2016-03/jhm-pcc031416.php

There’s always the Magic 8 Ball, but when it comes to determining life expectancy, some people want a little more scientific help. Thankfully, there are some useful tests and calculators to help us figure out how many more years we have left — at least until the Fountain of Youth is available in pill form. With that in mind, here are six ways to help predict whether you should keep on working and paying the mortgage or just blow it all on a big beach vacation.

Treadmill test
Want to know if you’ll survive the decade? Hop on a treadmill. Johns Hopkins researchers analyzed more than 58,000 stress tests and concluded that the results of a treadmill test can predict survival over the next 10 years. They came up with a formula, called the FIT Treadmill Score, which helps use fitness to predict mortality.

“The notion that being in good physical shape portends lower death risk is by no means new, but we wanted to quantify that risk precisely by age, gender and fitness level, and do so with an elegantly simple equation that requires no additional fancy testing beyond the standard stress test,” says lead investigator Haitham Ahmed, M.D. M.P.H., a cardiology fellow at the Johns Hopkins University School of Medicine.

In addition to age and gender, the formula factors in your ability to tolerate physical exertion — measured in “metabolic equivalents” or METs. Slow walking equals two METs, while running equals eight.

Researchers used the most common treadmill test, called the Bruce Protocol. The test utilizes three-minute segments, starting at 1.7 mph and a 10 percent grade, which slowly increase in speed and grade.

Researchers analyzed information on the thousands of people ages 18 to 96 who took the treadmill test. They tracked down how many of them died for whatever reason over the next decade. They found that fitness level, as measured by METs and peak heart rate reached during exercise, were the best predictors of death and survival, even after accounting for important variables such as diabetes and family history of premature death.

Sitting test
You don’t need special equipment for this adult version of crisscross applesauce that uses flexibility, balance and strength to measure life expectancy. Brazilian physician Claudio Gil Araujo created the test when he noticed many of his older patients had trouble picking things up off the floor or getting out of a chair.

To try, start by standing upright in the middle of a room. Without using your arms or hands for balance, carefully squat into a cross-legged sitting position. Once you’re settled, stand up from the sitting position — again, without using your arms for help.

You can earn up to 10 points for this maneuver. You get five points for sitting, five for standing, and you subtract a point each time you use an arm or knee for leverage or 1/2 point any time you lose your balance or the movement gets clumsy.

The test seems fairly simple, but Araujo found that it was an accurate predictor of life expectancy. He tested it on more than 2,000 of his patients age 51 to 80, and found that those who scored fewer than eight points were twice as likely to die within the next six years. Those who scored three points or even lower were five times more likely to die within the same time frame.

Araujo didn’t have anyone under 50 try the test, so the results won’t mean the same if you’re younger. As MNN’s Bryan Nelson writes, “If you’re younger than 50 and have trouble with the test, it ought to be a wake-up call. The good news is that the younger you are, the more time you have to get into better shape.”

Test your telomeres

A simple test may help determine your “biological age” by measuring the length of your telomeres. Telomeres are protective sections of DNA located at the end of your chromosomes. They’re sometimes compared to the plastic tips of shoelaces that keep the laces from fraying.

Each time a cell replicates, the telomeres become shorter. Some researchers believe that lifespan can be roughly predicted based upon how long your telomeres are. Shorter telomeres hint at a shorter lifespan for cells. Longer telomeres may mean you have more cell replications left.

Originally offered a few years ago only as an expensive — and relatively controversial — blood test in Britain, telomere testing in now available all over the world, and some companies even test using saliva. The results tell you where your telomere lengths fall in relation to other participants your age.

The link between genetics and longevity has been so embraced that testing companies have since been founded by respected scientists and researchers including Nobel laureate Elizabeth Blackburn of UC San Francisco and George Church, director of Harvard University’s Molecular Technology Group.

The increase in the number of at-home tests is getting the attention of concerned federal regulators and other researchers who question whether the science should stay in the lab.

“It is worth doing. It does tell us something. It is the best measure we have” of cellular aging, aging-researcher and Genescient CEO Bryant Villeponteau told the San Jose Mercury News. But testing still belongs in a research setting, he said, not used as a personal diagnostic tool.

As more people take them, he said, “I think the tests will get better, with more potential to learn something.”

Grip strength

Do you have an iron handshake or a limp fish grasp? Your grip strength can be an indicator of your longevity.

Recent research has shown a link between grip strength and your biological age. Hand-grip strength typically decreases as you age, although many studies have shown links between stronger grip strength and increased mortality.

You can keep your grip strong by doing regular hand exercises such as slowly squeezing and holding a tennis or foam ball, then repeating several more times.

Take a sniff

Does every little smell bug you? People who wear too much perfume? Grilled fish in the kitchen? A sensitive sense of smell is good news for your lifespan.

In a study last fall, University of Chicago researchers asked more than 3,000 people to identify five different scents. The found that 39 percent of the study subjects who failed the smelling test died within five years, compared to 19 percent of those with moderate smell loss and just 10 percent of those with a healthy sense of smell.

“We think loss of the sense of smell is like the canary in the coal mine,” said the study’s lead author Jayant M. Pinto, M.D., an associate professor of surgery at the University of Chicago who specializes in the genetics and treatment of olfactory and sinus disease. “It doesn’t directly cause death, but it’s a harbinger, an early warning that something has gone badly wrong, that damage has been done. Our findings could provide a useful clinical test, a quick and inexpensive way to identify patients most at risk.”

Life expectancy calculator

There are many online calculators that can serve up you estimated last birthday — thanks to some fancy algorithms. Some only take into account a few simple factors such as your age, height and weight. The better ones consider a range of variables including family health history, diet and exercise practices, marital and education status, smoking, drinking and sex habits, and even where you live.

Enter as much data as you can into an online form, like this one from researchers at the University of Pennsylvania, and click to get your results: http://gosset.wharton.upenn.edu/mortality/perl/CalcForm.html

Read more: http://www.mnn.com/health/fitness-well-being/stories/6-tools-to-help-predict-how-long-youll-live#ixzz3WScKjbUW